CN110637175A - Transverse section of drive belt for continuously variable transmission and drive belt including the same - Google Patents

Abstract

The invention relates to a transverse section (1) for a drive belt (50) having a ring stack (8) and having a transverse section (1) which is mounted on the ring stack (8) in the circumferential direction of the ring stack, comprising a base part (10) and two pillar parts (11), the pillar parts (11) extending in height direction from the side of the base part (10) in each case, wherein the upper side of the base part (10) between the pillar parts (11) defines a support surface (13a, 13b) and the pillar parts (11) each comprise a hook part (9) which extends in the direction of the respective opposite pillar part (11). The support surface (13a, 13b) comprises a substantially axially oriented central section (13b) and on at least one side thereof a side section (13a) oriented downwardly away from the central section (13 b). Thereby, mounting of the transverse segments (1) on the ring stack (8) for assembling the drive belt (50) is facilitated.

Description

Transverse section of drive belt for continuously variable transmission and transmission including the same moving belt

technical field

The present disclosure relates to a transverse section intended as part of a drive belt for a continuously variable transmission having two pulleys and a drive belt. Such drive belts are well known and are primarily used for running around two transmission pulleys between the pulleys respectively defining V-shaped grooves of variable width, the respective circumferential portions of the belt being held in V-shaped groove.

Background technique

Drive belts of known type comprise a substantially successive row of transverse segments mounted on endless belts or rings around the circumference of a plurality of endless belts or rings which are stacked on top of each other in radial direction . Each such transverse section defines a central opening that opens towards the radially outer side of the drive belt and accommodates and confines a corresponding circumferential section of such a ring stack while allowing the transverse section to move along its circumference. move. This particular type of drive belt is known, for example, from British Patent GB1286777 and European Patent Publication EP-1219860-A1.

In the above and following descriptions, axial, radial and circumferential directions are defined with respect to a drive belt placed in a circular posture. The thickness dimension of the transverse section is defined in the circumferential direction of the push belt, the height dimension of the transverse section is defined in said radial direction, and the width dimension of the transverse section is defined in said axial direction. A thickness dimension of the ring stack is defined in said radial direction and a width dimension of the ring stack is defined in said axial direction.

The transverse section is known to comprise a base and two studs extending from the base in radially outward direction, ie upwards in height direction, on either side of the base. A central opening containing the ring stack is defined by a base and two posts therebetween. Between the posts, said opening is delimited by a substantially axially aligned, radially outwardly facing support surface of the base which interacts with and supports the ring stack from its radially inner side. At least one, but preferably both studs of known drive belts are provided with hooks which extend in the axial direction over the central opening and thus are also partially closed in the radially outward direction. Thus, the bottom, i.e. the radially inner surface, of such a hook engages with the ring stack from its radially outer side, whereby the ring stack is accommodated in the radially outward direction in the central opening of the transverse section Inside.

To assemble the drive belt, it is generally not possible to fold the ring stack in the axial direction to allow it to pass between the hooks of the transverse sections and unfold in the central opening of the transverse sections. In particular, ring stacks can be damaged in practice due to such folding and unfolding thereof. Thus, that is, to mount the transverse sections on the ring stack, the transverse sections are each slid onto the unfolded, ie substantially rectangular cross-section, ring stack in a rotational orientation and then rotated axially to the ring stack. align. In order to allow such an installation, the overlap, ie the overhang, of the hooks of the transverse section and the ring stack in the axial direction must be small relative to the width of the ring stack. However, when this overlap is small, in particular less than the axial play of the transverse segment relative to the ring pack in the assembled belt, it may occur that the transverse segment separates from the ring pack during operation of the belt , which would compromise its integrity and continued operation.

It should be noted that, in principle, it is possible to increase the height of the central opening of the transverse section defined as the minimum distance in the radial direction between the support surface and the bottom surface of the hook, especially with respect to the thickness of the ring stack. This overlap, thereby increasing the radial clearance therebetween. In practice, however, this radial play must be small relative to the thickness of the ring stack in order to ensure the desired, ie optimum, performance of the drive belt. In practice, therefore, an alternative approach is taken for accommodating the ring stack in the central opening of the transverse section after mounting it on the transverse section. However, while many such alternatives have been proposed in the art over the years, they generally add cost and/or complexity to the drive belt or its assembly and thus have not been manufactured in large numbers.

Against the above background, the present invention sets out to improve the known drive belts equipped with transverse sections, the posts of which are each provided with hooks. In particular, the present disclosure seeks to increase the amount of overlap between such hook and loop stacks without compromising the generally high performance and low cost of existing drive belts.

Contents of the invention

According to the disclosure, the support surface comprises on at least one axial side thereof side sections which are oriented not only in the axial direction but also in the radially inward direction, ie with respect to the substantially axial orientation of the support surface The central section of is angularly oriented. By providing such side sections at an angle, the angle at which the ring stack is inserted into the central opening of this novel transverse section is increased compared to the insertion angles allowed by known transverse section designs. In turn, this increased insertion angle allows wider ring stacks to be assembled, thereby advantageously increasing the overlap.

Based on geometrical considerations, the side sections of the support surface preferably extend over a distance equal to or greater than the height of the central opening, in particular up to 2 times, preferably approximately 1.5 times, this height. Furthermore, said side sections preferably extend in a substantially straight line at least over a large part thereof. It is also preferred to provide a convexly curved transition section between said side sections and the central section of the support surface in order to avoid sharp edges forming therebetween and to avoid gaps in the ring stack and in the transverse direction during operation of the drive belt. Disadvantageously high contact stresses arise between the segments.

In the latter respect, it should be noted that support surfaces are also generally convexly curved. By such a convex shape of the support surface, for example as described in US Pat. No. 4,080,841, a preferred, ie centered, alignment of the ring stack relative to the support surface of the transverse section is intended. According to the invention, however, the radius of curvature of the support surface is much larger than that of the transition section, so as to be clearly distinguishable therefrom. More particularly, the radius of curvature of the support surface is at least 1 order of magnitude greater and preferably approximately 2 orders of magnitude greater than the radius of curvature of the transition section between said side and central sections of the support surface.

More particularly, according to the present disclosure, said extension surface is preferably positioned substantially coincident or radially inwardly with an imaginary, ie virtual, straight line drawn through:

- a first point defined by the transition between the side sections of the support surface and its central section; and

- A second point on the outer contour of the hook of the post on the opposite axial side of the support surface to the first point, the second point defining the axial extension of the inlet of the central opening towards the post.

The latter geometry of the transverse section allows it to be mounted advantageously on the ring stack without having to bend the latter, while achieving a relatively small value of said radial clearance and a relatively large value of said overlap.

Note that in the context of the present disclosure, ie for mounting the transverse segment to the ring stack, it is sufficient to provide a single extension surface on one axial side of the support surface. However, it may be preferable to provide extended surfaces on both axial sides of the support surface, so that the overall design and mass distribution of the transverse section can be symmetrical with respect to the radial direction (mirror plane), which in the field of transverse section design is idiomatic.

Description of drawings

The above described novel transverse section design according to the present disclosure will now be further explained with reference to the accompanying drawings, in which:

- Figure 1 is a simplified schematic side view of a variator with two pulleys and a drive belt comprising a ring stack and a row of transverse segments mounted along its circumference on the ring stack;

- Figure 2 schematically shows the known drive belt in a sectional view facing its circumferential direction and also comprising a separate side view of only its transverse section;

- Figure 3 schematically shows the assembly steps of the drive belt after the transverse sections have been folded and mounted on the ring stack;

- Figure 4 schematically shows the assembly steps of the drive belt in its natural, i.e. free shape or undeformed state, the mounting of the transverse segments on the ring stack;

- Figure 5 schematically shows the novel transverse section according to the disclosure in its front view;

- Figure 6 is an enlarged view of a detail of the novel transverse section of Figure 5, and

- Figure 7 shows further design details of the novel transverse section of Figure 5 .

Detailed ways

Fig. 1 schematically shows a central part of a continuously variable transmission 100 for a drive train of eg a passenger motor vehicle. This transmission 100 is well known and includes at least a first variable pulley 101 and a second variable pulley 102 . In a drive train, the first pulley 101 is coupled to and driven by a main machine, such as an electric motor or an internal combustion engine, and the second pulley 102 is coupled to and drives drive wheels of a motor vehicle, typically via a plurality of transmissions.

Each of the transmission pulleys 101, 102 generally includes: a first conical pulley plate fixed to the pulley shaft 103, 104 of the respective pulley 101, 102; The pulley shafts 103 , 104 are axially displaced and are only relatively non-rotatably fixed to the respective pulley shaft 103 , 104 . The transmission belt 50 of the transmission 100 is wound on the pulleys 101, 102 while being accommodated between the pulley pulleys thereof. As shown in FIG. 1, the track of the transmission belt 50 in the transmission 100 includes two straight sections ST and two curved sections CT, in which the transmission belt 50 is wound on a corresponding one of the two transmission pulleys 101, 102. . The drive belt 50 consists of a ring stack 8 and a plurality of transverse segments 1 which are mounted on the ring stack 8 in at least approximately successive rows in the circumferential direction of the ring stack 8 . For simplicity, only some of these transverse sections 1 are shown in FIG. 1 . In the drive belt 50 the transverse section 1 is displaceable in the circumferential direction of a ring stack 8 which generally consists of a plurality of flexible endless metal bands or rings stacked on top of each other, ie nested in each other. During operation of the transmission 100 the transverse section 1 of the drive belt 50 at the first pulley 101 is driven by friction in its direction of rotation. These driven transverse sections 1 push the preceding transverse section 1 along the circumference of the ring stack 8 of the drive belt 50 (the ring stack 8 itself may be rotating) and finally drive the second rotationally again by friction. Pulley 102. In order to generate this friction (force) between the transverse section 1 and the variator pulleys 101 , 102 , said pulley disks of each pulley 101 , 102 are pressed against each other, whereby they move on the transverse section 1 It exerts a clamping force in the axial direction. For this purpose, electronically controlled and hydraulically-acted movement means (not shown) acting on the movable pulley discs of each pulley 101 , 102 are provided in the transmission 100 . In addition to exerting a clamping force on the drive belt 50, these kinematic devices also control the respective radial positions R1 and R2 of the drive belt 50 at the pulleys 101, 102 and, therefore, control the variator 100 provided between its pulley shafts 103, 104. speed ratio.

In Fig. 2, a known drive belt 50 is schematically shown. On the left in FIG. 2 , the drive belt 50 is shown in section and on the right in FIG. 2 only includes a side view of its transverse section 1 . It can be seen from FIG. 2 that the shape of the transverse section 1 of the drive belt 50 is similar to the letter "V", that is, roughly V-shaped. In other words, the sides 12 of the transverse section 1 that are in contact (rubbing) with the variator pulleys 101 , 102 are oriented to each other at an angle that closely matches the angle that exists between the conical pulley disks of the variator pulleys 101 , 102 . These pulley contact surfaces 12 are corrugated or have a rough surface structure by macroscopic profile, so that only the higher peaks of the corrugation profile or surface roughness come into contact with the transmission pulleys 101 , 102 . This particular feature of the transverse section design enables the cooling oil applied between the drive belt 50 and the transmission pulleys 101, 102 to be accommodated in the lower portion of the corrugated profile or surface roughness in the known transmission 100. friction is optimized.

Each transverse section 1 defines a base 10 and two pillars 11, wherein the base 10 extends substantially in the axial direction of the drive belt 50, and the pillars 11 extend substantially in the radial direction of the drive belt 50 respectively from The respective axial sides of the base 10 extend. In its thickness direction, each transverse segment 1 extends between its front face 3 and rear face 2 , each of which is oriented at least approximately in the circumferential direction of the drive belt 50 . Centrally defined between the post 11 and the base 10 of each transverse section 1 is an opening 5 in which a circumferential section of the ring stack 8 is accommodated. The radially outward portion 13 of the peripheral surface of the base, hereinafter referred to as support surface 13 , forms the radially inner boundary of the central opening 5 , supporting the ring stack 8 from the radially inner side. This support surface 13 is generally convexly curved in order to facilitate a preferred centered alignment of the ring stack 8 during operation, ie rotation, of the drive belt 50 in the transmission 100 .

In a row of transverse sections 1 of the drive belt 50, at least a part of the front body surface 3 of a transverse section 1 abuts at least a part of the rear body surface 2 of the corresponding preceding transverse section 1 in the row, while At least a part of the rear body surface 2 of a transverse section 1 abuts at least a part of the front body surface 3 of the corresponding subsequent transverse section 1 . Adjacent transverse sections 1 can be inclined relative to each other while being kept in mutual contact at the front surface 3 thereof by an axially extending and radially curved curved surface portion 4 , referred to hereinafter as inclined Edge 4. Below the beveled edge 4, as seen in the side view of FIG. The corresponding base 10 of the adjacent transverse segment 1 is disturbed. Note that although in FIG. 2 the beveled edge 4 is located in the base 10 of the transverse section 1 , it is also known to locate it at least partially in the post 11 , ie in two axially separated but radially aligned regions. section (not shown).

The pillars 11 of the transverse section 1 are each provided with a protrusion 6 which protrudes substantially in said circumferential direction from the respective front face 3 . In the drive belt 50, the protrusions 6 are inserted into the recesses 7 provided in the opposite, i.e. the rear surface 2, of the adjacent transverse section 1, so as to limit the relative movement at least in the radial direction but generally also in the axial direction. Relative movement between adjacent transverse segments 1 .

The columns 11 of the transverse section 1 are also each provided with a hook 9 which overhangs the opening 5 in the axial direction. The hook 9 , in particular its bottom surface, ie its radially inward surface 14 also partially closes the central opening 5 in the radially outward direction. In the drive belt 50 , the hooks 9 of the transverse section 1 overlap the ring pack 8 in the axial direction and thus prevent or at least hinder a possible separation of the transverse section 1 from the ring pack 8 in the radially inward direction.

As shown schematically in FIG. 3 , in order to assemble a drive belt 50 according to the above-mentioned known design, the ring stack 8 has to be bent considerably in the axial direction, that is to say folded in almost two layers, in order to pass through the belt formed by the transverse section 1 The hooks 9 define between them the entrance to the central opening 5 . In practice, however, such a considerable elastic deformation of the ring stack 8 is generally not possible due to the high stiffness and low yield strain of the ring material. In this respect, FIG. 4 schematically shows a more practical method of drive belt assembly in which the ring stack 8 does not need to be deformed, at least not significantly. In FIG. 4 , the dotted rectangular outline schematically shows the position of the undeformed ring stack 8 relative to the transverse section 1 during drive belt assembly, ie when the transverse section 1 is mounted on the ring stack 8 . Note that in practice the individual rings and thus the entire undeformed ring stack 8 are usually slightly curved, i.e. convex, in the width direction, so that the effective thickness of the ring stack 8 in its described undeformed state is slightly greater than its physical thickness.

A limitation of the particular method of drive belt assembly shown in FIG. 4 is that the hooks 9 of the transverse section 1 can overlap only a small amount with the ring stack 8 in the axial direction. In other words, the width W8 of the ring stack 8 can only be slightly greater than the width EW5 of the gap between its hooks 9 which provides access to the central opening 5 of the transverse section 1 . In particular, in the assembled state of the drive belt 50, the maximum possible overlap between the ring stack 8 and the hook 9 (ie W8 minus EW5) can be compared with the radial clearance RC between the ring stack 8 and the hook 9 geometrically related. However, on this type of drive belt 50 this radial clearance RC needs to be limited, in particular to less than 30% of the (effective) thickness of the ring stack 8 , preferably in the range between 15% and 25%. This makes the maximum possible overlap disadvantageously small. Thus, with this drive belt design and its method of assembly, there is a risk of separation of the cross member 1 from the ring stack 8 during operation of the drive belt 50 . Such separation may occur in particular when, in the row of transverse sections of the drive belt 50, gaps are formed on either side of the transverse section 1, for example due to wear of the belt 50 during the service life of the variator and high transient belt loads . If said overlap could be increased somehow, the risk of separation could be reduced.

According to the present disclosure, the width W8 of the ring stack 8 can be increased relative to the gap width EW5 of the opening 5 between the hooks 9, as schematically shown in FIG. 5 in an exemplary embodiment of the novel transverse section 1, The overlap, ie the (combined) overhang of the hook 9 over the ring stack 8 is also increased. In the novel transverse section 1 , the support surface 13 does not extend substantially in the axial direction over the entire width of the opening 5 between the pillars 11 , but comprises side regions on either axial side of its central section 13b The segment 13a, the side segment 13a, is oriented away from said central segment 13b of the support surface 13 in a radially inward direction. In particular, the side sections 13a are oriented at an acute angle relative to the central section 13b. A preferred, practically applicable range of such angles is 10 to 30 degrees, more particularly 15 to 25 degrees.

With this design feature of the novel transverse section 1 , when it is mounted on the ring stack 8 , one axial side of the ring stack 8 extends radially inside the support surface 13 , in particular more or less Parallel to one of the side sections 13 a of the support surface 13 . Thus, a much wider ring stack 8 can be inserted into the central opening 5 of the novel transverse section 1 compared to the known transverse section 1 of FIG. 4 with the central opening 5 of the same gap width EW5 . Thereby, said overlap of the hooks 9 of the transverse section 1 with the ring stack 8 is advantageously increased with respect to said radial gap RC therebetween. Alternatively, it may be advantageous to reduce the radial clearance RC, or a combination of both.

In particular, the side section 13a is located completely below the hook 9 of the corresponding column part 11 , ie the side section 13a remains within the axial extension of the corresponding hook 9 and the central section 13b is positioned within the corresponding hook 9 . Start within the axial extension of section 9. As shown in more detail in FIG. 6 with an enlarged view of the transverse section of FIG. 5, preferably a convexly curved transition section 13c of the support surface 13 is provided between said side sections 13a and the central section 13b thereof between. Such a transition section 13c avoids sharp edges and disadvantageously high contact stresses between the ring pack 8 and the transverse section 1 during operation of the drive belt 50 . Also in FIG. 6 , it is shown that the central section 13 b of the support surface 13 is also generally convexly curved, however, compared to the radius of curvature R10 of, for example, 10 mm for the transition section 13 c, the central section 13 b is, for example, at a relatively smaller Large 300mm radius of curvature R300 convex bend.

Finally, two preferred geometrical aspects of the novel transverse segment 1 are shown in FIG. 7 . Firstly, the respective side section 13a of the support surface 13 is located radially inside a first imaginary straight line L1 drawn through the following points:

- a first point P1 between such respective side section 13a and central section 13b of the support surface 13, and

- a second point P2 on the outer contour of the hook portion 9 of the column portion 11 on the opposite axial side of the support surface 13 to the first point P1, the second point P2 delimiting the entrance of the central opening 5 towards the axial extension of the column portion 11 .

As a result, unfavorable contact between the ring stack 8 and the respective side section 13 a of the support surface 13 can be largely avoided during assembly of the drive belt 50 .

Secondly, the corresponding top surface, that is, the radially outer surface 15 of the hook portion 9 of the column portion 11 is located radially inside (or at most substantially coincident in the radially outward direction) of the second imaginary straight line L2, said second A virtual straight line L2 is drawn through the side section 13a on the opposite side of the support surface 13 with respect to this corresponding column portion 11 . Thereby, during the assembly of the drive belt 50 , unfavorable contact between the ring stack 8 and the respective top surface 15 of the hook 9 can be largely avoided.

The present disclosure relates to and includes all features of the claims, in addition to all details of the foregoing full description and drawings. Reference signs in the claims do not limit their scope but are provided only as a non-limiting example of corresponding feature. As the case may be, claimed features may be applied individually in a given product or in a given process, but any combination of two or more such features may also be applied therein.

The disclosure represented by this disclosure is not limited to the embodiments and/or examples explicitly mentioned here, but also includes corrections, modifications and practical applications thereof, particularly those that would occur to those skilled in the art.

Claims (7)

1. Transverse segment (1) for a drive belt (50), which drive belt (50) has a ring stack (8) and has a transverse segment (1) mounted on the ring stack (8) in the circumferential direction of the ring stack (8), which transverse segment (1) comprises a base part (10) and two pillar parts (11), which pillar parts (11) extend in the height direction from the sides of the base part (10), wherein the upper side of the base part (10) between the pillar parts (11) defines a support surface (13a, 13b), at least one of the pillar parts (11) comprising a hook part (9) extending in the width direction in the direction of the respective opposite pillar part (11), characterized in that the support surface (13a, 13b) comprises a central section (13b) oriented substantially in the width direction and comprises a side section (13a) on at least one side of the support surface (13a, 13b), the side section (13a) is oriented at an acute angle to the central section (13b) and downward in the height direction away from the central section (13b), the side section (13a) being located below the hook (9) of the at least one post (11) in the height direction.

2. The transverse section (1) according to claim 1, characterized in that the hook (9) of the at least one pillar (11) extends in the direction of the respective opposite pillar (11) over the entire extension of the side section (13a) of the support surface (13a, 13b) in the direction of the respective opposite pillar (11).

3. The transverse section (1) according to claim 1 or 2, characterized in that the side sections (13a) of the support surfaces (13a, 13b) extend over a distance which is equal to or greater than the distance in height direction between the hook (9) of the at least one post (11) and the central section (13b) of the support surfaces (13a, 13b), and preferably equal to about 1.5 times the distance in height direction between the hook (9) of the at least one post (11) and the central section (13b) of the support surfaces (13a, 13 b).

4. The transverse section (1) according to claim 1, 2 or 3, characterised in that the central section (13b) of the support surface (13a, 13b) extends in the width direction substantially parallel to and over the entire width of the gap between the post (11), the respective hook (9) or the hook (9) of the post (11).

5. The transverse section (1) according to any one of the preceding claims, characterized in that a central section (13b) of the support surface (13a, 13b) is located centrally in the width direction between two posts (11), both posts (11) comprising hooks (9) extending in the width direction towards the respective opposite post (11), respectively, and the support surface (13a, 13b) is provided with said side sections (13a) below the respective hooks (9) on both sides of its central section (13 b).

6. Drive belt (50) with a ring stack (8) and a plurality of transverse segments (1) according to any one of claims 1 to 5, the transverse segments (1) being mounted on the ring stack (5) in the circumferential direction of the ring stack (5), while the ring stack (8) is located essentially in the middle of the base (10) of the respective transverse segment (1) in the width direction and is in contact with the central section (13b) of the support surface (13a, 13 b).

7. Drive belt (50) consisting of only one ring stack (8) and a plurality of transverse segments (1) according to any one of claims 1 to 5, which transverse segments (1) are mounted on the ring stack (8) in the circumferential direction of the ring stack (5).